The proposed research involves social, genetic and environmental factors influencing puberty in mammals. These investigations have significance for and applications to our understanding of development, behavioral biology and animal populations. (1) Menarche in human females is a critical time in the psychosexual development of the individual. Studies of factors affecting puberty in another mammal species can provide information for discerning questions to ask about humans. (2) Mice are resevoirs for and vectors of disease and they are agricultural pests. The proposed research investigates two models of population regulation in rodents via changes in generation time. (3) Increasing evidence that olfactory stimuli affect social behavior in mammals, including man, necessitates experiments on chemosignals, their production and effects on physiology and behavior. (4) The use of social and olfactory stimuli to affect puberty in domestic livestock is, in part, an outgrowth from work on rodents. Proposed experiments will utilize house mice as subjects and first vaginal estrus as a dependent variable indicting puberty. Major aims are to explore further the genetic and social factors which influence puberty, to test two models of population regulation in mice and to examine social and environmental influences upon urinary chemosignal release. Four lines of experimentation are proposed; (a) investigations of genetic influences on puberty via a dialell cross, selection for age of puberty in wild mice and examining differential survival of genotypes under various pre- and post-natal social conditions, (b) experiments on daylength and temperature as environmental influences on the production/release of urinary chemosignals, (c) tests of social influences on puberty; experiments involving circannual rhythms, anosmia and hormones, as they affect the chemosignals which accelerate and delay sexual maturation, and (d) tests of the mechanisms by which these signals affect puberty in young female mice.